The invention pertains to a method for operating a traction vehicle and to a traction vehicle.
Methods and traction vehicles of the type addressed here are known. In addition to diesel-electric locomotives, which comprise a single, high-power internal combustion engine functionally connected to a generator for producing electric power, wherein at least one traction motor is provided to convert the electric power into drive power, diesel-electric traction vehicles are also known which comprise at least two typically less powerful internal combustion engines, each of which is functionally connected to a generator, one of which is assigned to each of the individual internal combustion engines, to produce electric power. A composite system consisting of an internal combustion engine and a generator of this type is also called a “generator set” or GenSet for short. These traction vehicles also comprise at least one electric traction motor, preferably several of them, which are designed to convert electric power into drive power. During the operation of a traction vehicle of this type comprising a drive system of the type in question consisting of at least two generator sets, the power delivered by the drive system is produced by the at least two internal combustion engines. Regardless of whether a single, high-power internal combustion engine or several internal combustion engines less powerful than the single internal combustion engine are provided, diesel-electric traction vehicles are typically operated in such a way that a previously determined number of separate power stages is provided, which range from a minimum power stage to the nominal power of the drive system. The nominal power of the drive system corresponds to the maximum sustained power output.
It can be observed that the power stages in the known traction vehicles or in the methods for their operation are distributed nonuniformly over the power range. Comparatively many power stages are provided especially in the low power range, these stages being comparatively close together—as measured in power units—whereas comparatively few power stages farther away from each other are provided in the higher power range. For example, a first minimal power stage is provided at 4.5% of nominal power, whereas a second power stage lies at 11.5% and a third power stage at 23.5%. In contrast, the three highest power stages are at 64%, 85%, and 100%.
The result is that, when in the lower power range of the drive system, the internal combustion engine intended to produce the drive power is always being used at far below its full load. As a result, it operates in a range which is especially unfavorable with respect to efficiency and specific emissions. In addition, internal combustion engines (ICEs) which are typically designed for continuous operation at full load can hardly be used in a traction vehicle of this type, because they are not intended to be operated for prolonged periods under low, partial-load conditions.